1. Field of the Invention
The present invention relates to a transfer apparatus which is used for moving a heavy load at least in upward and downward directions, i.e., for elevating the heavy load and which has a fall preventing mechanism, and also relates to a prober which incorpolates the transfer apparatus as means for moving a test head.
2. Description of the Related Art
A prober is used to test electric characteristics of semiconductor devices (or semiconductor chips) formed on a semiconductor wafer, an LCD substrate, or the like. An example of a conventional prober is shown in FIGS. 18 and 19. The main body 2 of the prober is provided with a work table 4 which is movable in the X- and Y-directions in a horizontal plane and in a Z-direction which is a vertical direction. An object to be probed, for example, a semiconductor wafer W is mounted on the upper surface of the work table. A ring-like probe card 8 provided with a plurality of probe needles 6, and an interface section 10 having a contact with the upper surface of the card and electrically connected with the probe card 8 are detachably secured to the upper surface of the main body 2.
A test head 12 is rotatably supported at a side portion of the main body 2 and can stand or lie on the upper surface of the main body 2. A contact ring 14 for making electric contacts with a number of polygonal pins provided in the interface section 10. Wiring bundle 16 consisting of a number of wirings extending from the test head 12 is connected to a tester 18 with which electric characteristics of an object are tested.
When the position of electrode pads is changed on an object, the probe card 8, the contact ring 14, and the like must be exchanged so as to comply with the changed position. In this state, the test head 12 which has a weight up to about 300 kg is manually rotated to stand, thereby to perform exchange services. In addition, the test head 12 must be rotated in the same manner when the contact ring 14 and the probe card 8 are subjected to maintenance services.
In these cases, the operational efficiency and the security are not excellent since this test head 12 is manually operated so as to stand or lie by an operator, as has been explained above.